Treatment of fibrous materials



3,07 3,430 TREAH MhNT F FEBRGUS MATERIALS Henry Bristow MeCance and Frederick R. W. Sloan, Ballyclare, Northern Ireland, assignors to Bleachers Association Limited, Manchester, England No Drawing. Filed Mar. 3, 1958, Ser. N 718,400 laims priority, application Great Britain Mar. 11, 1957 3 Claims. (l. 8-116A) The invention relates to a process for treating cellulosic fabrics, such as cotton or regenerated cellulose fabrics which may be woven or knitted fabrics or felts to produce a so-called drip-dry finish thereon, i.e. a finish requiring little or no ironing after washing.

it has already been proposed to treat such fabrics with a polyvinyl alcohol and formaldehyde to assist the retention of mechanical effects such as glazing or embossing, or to produce crease-resistant fabrics. Such prior processes aim at producing crease resistance in the dry state. The aim of the present process on the contrary is to produce a high crease resistance in the wet state, there being little or no increase in dry crease angle over that normally obtainable. An important feature of the invention is that it enables fabrics to be produced which have a high ilexural rigidity and at the same time excellent wet crease resistance. In this particular instance the dry crease angle will be decreased somewhat. This is important for producing interlinings for drip-dry shirtings made from either cotton or synthetic materials or mixtures thereof.

In accordance with the invention the cellulosic fabric is treated in aqueous medium with a polyvinyl alcohol, a cross linking agent containing at least two hydroxyl groups in the molecule, and a water-soluble polyester containing free carboxylic groups.

Where stff eilects are required the polyvinyl alcohol should preferably be of medium to high viscosity and be not less than 97% hydrolysed, otherwise a low viscosity polyvinyl alcohol should preferably be used.

In carrying the invention into effect the fabric as stated above may be composed of cotton or regenerated cellulose. The cross linking agent may conveniently be formaldehyde which is, of course, bifunctional in the hydrated state or may be a compound of formaldehyde which is at least bifunctional. Such a compound may be glyoxal, a hemi-acetal or a methylolated derivative of formaldehyde or it may be a dialdehyde.

Such cross linking agents react both with the polyvinyl alcohol and with the cellulose molecule. The cross linking agent may also comprise a mixture of one of the above compounds with free formaldehyde. The polyvinyl alcohol may be water-soluble or dispersible in water. The polyester used as a catalyst may be produced by in complete esterification of a monocarboxylic or polycarboxylic acid or anhydride with a monohydric or polyhydric alcohol. The starting materials used to produce the polyester products may be polybasic acids especially dibasic acids, such for example as sebacic acid, maleic acid, succinic acid or phthalic acid or anhydrides thereof, and polyhydric alcohols such for example as glycols or glycerol. It is essential that the polyester products should have free carboxyl groups and this is readily obtained by having the acid component in substantial excess of the alcohol component.

As the polyester products are of a resinous nature, complete ionisation of the carboxyl groups is restricted in the dry state, so that the material can be dried into cellulosic textile materials without acid degradation. This enables lower pH values to be realised than is possible with the free acid, so that faster and more complete polymerisation can be achieved where resin finishes are Patented Jan. 1, 1963 applied to cellulosic or the like materials. Moreover, cross linking reactions with cellulose are greatly facilitated by the use of such a polyester product and since the polyhydroxyl substrate is both cellulose and polyvinyl alcohol, the two latter components are joined together in addition to being cross linked themselves.

A suitable polyester product can be made, for example by reacting triethylene glycol and su-ccinic acid in the ratio of 0.5 :1 and carrying out the reaction in a vented stainless steel reaction vessel in a slow stream of inert gas. The temperature of the reaction is maintained for about 2 hours at 170 C., and is then raised to 190 C. and held until the acid value reaches 250. On cooling the polyester product presents a gel like appearance.

To obtain the best results the treatment of the fabric is effected at a pH value not greater than 2.4. The invention may be effected by impregnating woven, knitted fabrics or felts with the ingredients referred to above, dissolved or dispersed in aqueous medium and subsequently squeezed to about percent expression followed by drying and heating of about 3 minutes at a temperature of C. to complete the reaction. v

The invention is further illustrated by the following examples.

Example 1 Interlining finish on spun ray0n.10 grams of polyvinyl alcohol 97% hydrolysed of medium viscosity are dissolved in 80 mls. water at about 90 C. When cooled to approximately 25 C. 10 grams of climethylol ethylene urea and 10 grams of tetra methylol acetylene di-urea, e.g. Fixapret 140 are then added, followed by 2 grams of polyester product dissolved in 20 mls. of water.

A length of spun rayon weighing 5 ozs. per sq. yard is passed through this solution and squeezed and dried. The length is then cured for 3 /2 minutes at C. The fabric has a wet crease resistance of a very high order and also much improved abrasion resistance. Also, it is stabilised to both warp and weft shrinkage and has decreased capacity for water absorption. This material may be used to produce a drip dry cotton etc.

Example 2 A drip-dry finish on cotton p0plin.--l gram of polyvinyl alcohol 97% hydrolysed and of medium viscosity (a suitable product is commercially available under the name Polyviol 05/20) are dissolved in 80 mls. hot Water. When cooled, 25 grams of ethyl methyl dimethylol urea followed by 2 grams of polyester condensation product dissolved in 20 mls. Water and 5 grams of 40% w./v. solution of formalclahyde are then added. A piece of poplin which has been suitably prepared is passed through the solution and dried and cured for 3 /2 minutes at 130 C. Thereafter, the material may be washed off in soap and soda ash. A good crease resist effect when Wet is obtained with superior resistance to abrasion stability and washing, garments made from the fabric requiring little or no ironing after washing.

Example 3 Drip-dry interlining finish on spun ray0n.l0 grams of polyvinyl alcohol 97 hydrolysed of medium viscosity a suitable product is commercially available under the name Polyviol W28/20) are dissolved in 80 mls. water at about 90 C. When cooled to approximately 25 C., 21 grams of tetra methylol acetylene di-urea (a suitable material is available under the name Fixapret is then added, followed by 5 grams of 40% w./v. solution of formaldehyde and finally 2 grams of a polyester product dissolved in 20 mls. of water.

A length of spun rayon weighing 5 ozs. per sq. yard is passed through this solution and squeezed and dried.

The length is then cured for 3 /2 minutes at 130 C. The fabric has a wet crease resistance of a very high order and also much improved abrasion resistance. Also, it is stabilised to both warp and weft shrinkage and has decreased capacity for water absorption. Garments made from the fabric require little or no ironing after washing.

Example 4 Interlining finish on a cotton-5 grams of polyvinyl alcohol 97% hydrolysed (a suitable product is Polyviol W28/20) is dissolved in 80 mls. of water at about 90 C. When cooled to about 25 C. grams of dimethylol ethylene urea is added and 2 grams of the polyester product dissolved in 20 mls. of water.

A length of cotton material weighing 8.5 02. sq. yard is passed through this solution, squeezed at about 80% expression and dried.

The material is then cured for 3 minutes at 130 and finally washed through alkali and dried.

A very high wet crease resistance is obtained together with stiffness.

In all the above examples the polyester product employed was the product produced by incomplete esterification of succinic acid with ethylene glycol.

We claim:

1. A process for imparting a drip-dry finish to cellulosic fabric which comprises impregnating the fabric with an aqueous solution of (1) polyvinyl alcohol, (2) a polyvinyl alcohol-cellulose cross-linking agent containing at least two hydroxyl groups and (3) a water soluble polyester comprising the polycondensation product of a saturated polyhydric alcohol with a substantial excess of a saturated polycarboxylic acid, said polyester containing free carboxyl groups and being present in an amount sulhcient to impart a pH of not greater than 2.4 to the solution, drying the impregnated fabric and heating it to react the crossiinlring agent with the polyvinyl alcohol and the cellulose of the fabric.

2. A process as claimed in claim 1 in which the cross linking agent is selected from the group consisting of hydrated formaldehyde and polymethylolated derivatives of formaldehyde.

3. A process as claimed in claim 1 in which the cross linking agent is a mixture of formaldehyde and a polyrnethylolated derivative of formaldehyde.

References Cited in the file of this patent UNITED STATES PATENTS 2,259,225 Kienle et al Oct. 14, 1941 2,295,699 Thacksten 11 Sept. 15, 1942 2,341,735 Monsaroff Feb. 15, 1944 2,725,308 Nickerson Nov. 29, 1955 2,755,198 Stewart July 17, 1956 FOREIGN PATENTS 568,388 Great Britain Apr. 3, 1945 OTHER REFERENCES Schildknecht, C. E.: Vinyl and Related Polymers, p. 354, John Wiley and Sons, Inc., New York (1952). 

1. A PROCESS FOR IMPARTING A DRIP-DRY FINISH TO CELLULOSIC FABRIC WHICH COMPRISES IMPREGNATING THE FABRIC WITH AN AQUEOUS SOLUTION OF (1) POLYVINYL ALCOHOL, (2) A POLYVINYL ALCOHOL-CELLULOSE CROSS-LINKING AGENT CONTAINING AT LEAST TWO HYDROXYL GROUPS AND (3) A WATER SOLUBLE POLYESTER COMPRISING THE POLYCONDENSATION PRODUCT OF A SATURATED POLYHYDRIC ALCOHOL WITH A SUBSTANTIAL EXCESS OF A SATURATED POLYCARBOXYLIC ACID, SAID POLYESTER CONTAINING FREE CARBOXYL GROUPS AND BEING PRESENT IN AN AMOUNT SUFFICIENT TO IMPART A PH OF NOT GREATER THAN 2.4 TO THE SOLUTION, DRYING THE IMPREGNATED FABRIC AND HEATING IT TO REACT THE CROSSLINKING AGENT WITH THE POLYVINYL ALCOHOL AND THE CELLULOSE OF THE FABRIC. 